Many types of fuel filters and separators are known in the prior art. A popular type of filter and/or separator construction is a type that has a filter head to which a replaceable "spin-on" element is attached. The head is a permanent part of the fuel system of the vehicle and includes inlet and outlet connections to the fuel lines. The element may be readily removed from the filter head and a new one attached without opening the fuel line connections to the filter head.
Another popular type of fuel filter construction is one that has a housing which encloses a replaceable filter element.
Problems may arise when such filter elements are replaced. Periodic replacement of the element ensures that the filter element will not become so loaded with impurities that fuel flow is restricted. Replacing the element also ensures that impurities are removed from fuel before it is delivered to other fuel system components such as fuel injection pumps and fuel injectors, where such contaminants may cause severe damage.
One common problem associated with changing filters is fuel spillage. The fuel lines and element are often under pressure. When the element is removed the pressure is relieved and the fuel spills out. This can present a fire hazard as well as a waste clean up problem.
A further problem is that filter elements with different filtration capabilities often have an identical mounting configurations and may fit on the same filter head. However, use of the wrong filter can cause poor engine performance and allow undesirable amounts of contaminants, which shortens engine life.
Another problem is that disturbance of the spent element during replacement may cause collected impurities to fall off the element. In some designs, these impurities may travel into the outlet of the filter housing. As a result these contaminants may reach the components downstream in the fuel system.
Another problem is that changing the element may require a mechanic to have skin contact with the fuel. It is desirable to minimize such contact when changing a filter element.
To reduce and at least partially eliminate these problems, the filter element shown in U.S. Pat. No. 4,836,923, owned by the Assignee of the present invention, was developed. This filter assembly includes a replaceable filter element that is attached to a removable cover. This construction enables changing the element while avoiding skin contact with fuel.
A further advantage of this element design is that it has an internal standpipe with an opening at the top. When the element is removed from the housing, the fuel level in the housing falls below the opening to the standpipe. As a result, the impurity-laden fuel left in the housing is less likely to reach the outlet. Likewise, when a new element is installed in the housing, only fuel that has been purified by passing through the media of the element is enabled to reach the opening and pass out of the assembly.
While this element design has many advantages, if the filter element is not removed carefully, impurity-laden fuel in the housing or from the outer surface of the element may fall into the opening in the standpipe. If this happens, some impurities may reach the downstream components of the fuel system.
In addition, the cover is discarded with each spent element. This is undesirable from a conservation and solid waste standpoint. It is generally desirable to minimize the amount of material discarded, particularly if a discarded element must be treated as hazardous waste. The cover also represents a portion of the cost of the replacement element. As a result this design adds cost to the replacement element. Sometimes individuals who do not care about maintaining the vehicle on which the prior art filter assembly is used, may separate the element from the attached cover portion and install the cover on the housing without the element. This causes the vehicle to operate without fuel filtration until the problem is discovered. If the vehicle is operated for an extended period of time in this condition, damage to fuel system components may occur.
In any case, it is believed that there exists a need for a fuel filter that has increased reliability, reduces waste, is low in cost, minimizes skin contact during element changes, and minimizes the risk that an improper filter will be used and minimizes fuel spillage.